Hydrogen and Oxygen Isotope Fractionation in Water during Gas Hydrate Formation

• Published in: Annals of the New York Academy of Sciences
• Main Authors: MAEKAWA, TATSUO, IMAI, NOBORU
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2000
• Subjects: History and Philosophy of Science; General Biochemistry, Genetics and Molecular Biology; General Neuroscience; Methane hydrate
• Online Access: http://dx.doi.org/10.1111/j.1749-6632.2000.tb06800.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1749-6632.2000.tb06800.x; https://nyaspubs.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1749-6632.2000.tb06800.x

A bstract : Isotope fractionation of hydrogen and oxygen in water caused by methane hydrate formation in saline water was investigated experimentally. The isotope fractionation factors were calculated by measuring the concentration of salts and hydrogen and oxygen isotopic ratios of water in both initial solution and residual solution after formation of methane hydrate. The amount of methane hydrates was estimated using two assumptions: complete desalination and gas consumption. As methane hydrate forms in saline water, the concentration of salt in solution increases and gas pressure decreases. We estimated the amount of methane hydrate not only from the increase of concentration of salts in the solution, but also from the decrease in gas pressure. The isotope fractionation factors of hydrogen and oxygen in the water between methane hydrate and saline water were obtained as 1.016 to 1.020 and 1.0028 to 1.0032, respectively. These are similar to the factors between ice and water.